The Federal Reserve reduced rates on Wednesday, but against expectations the head of the US central bank said the move might not be the start of a lengthy series of cuts to shore up the economy against global economic weakness.

Brent crude, the international benchmark, fell $1.08 to $63.97 a barrel by 1327 GMT, having dropped as low as $63.73 earlier in the session. US West Texas Intermediate (WTI) crude was down $1.47 at $57.11.

"A relatively upbeat mood in risky assets took a spectacular U-turn after last night's Fed decision," Tamas Varga of oil broker PVM said. "The dollar started to strengthen and equities and oil went into a kind of meltdown mode."

A rising dollar makes oil more expensive for holders of other currencies and tends to weigh on commodities priced in the US currency. The dollar hit a two-year peak against the euro on Thursday after the Fed decision.

Oil's drop came despite a bigger-than-expected decline in US inventories and a fall in OPEC production in July, typically bullish drivers for prices. But US output rose in a market that analysts say is well supplied.

"Supply is plentiful and demand growth is showing signs of weakening globally because of trade conflicts, Brexit and other events that tend to potentially weaken economic growth and, hence, oil demand," Victor Shum, senior partner at IHS in Singapore, said.

"There's a lot of oil out there. US output is growing strongly."

OPEC and partners including Russia, an alliance known as OPEC+, have been curbing output this year to support the market. In July, OPEC production revisited a 2011 low, helped by a further cut by Saudi Arabia, a Reuters survey showed.

But rising supplies from non-aligned producers including the United States have offset the OPEC+ efforts. US output rebounded to 12.2 million barrels per day (bpd) from 11.3 million bpd a week earlier, government data showed on Wednesday.

Adding further downward pressure on prices was a lack of progress by the United States and China in resolving their year-long trade dispute. Negotiators ended talks on Wednesday and agreed to meet again in September.